It's been 38 years since the continental United States experienced a total solar eclipse. The rare celestial event is generating interest and enthusiasm across the country and world, with cities along the eclipse's path expected to attract thousands of visitors.

Here's a look at the eclipse by the numbers:

4 The number of continents where at least a partial eclipse will be visible.

14 The number of states in the path of the total eclipse.

15 The temperature can drop by this many degrees during totality.

70 The width in miles of the path of totality -- the area where the total eclipse will be visible.

99 The number of years since a total solar eclipse crossed over the entire U.S. mainland.

146 The maximum number of seconds when the sun will be completely covered in Casper.

4:09 The time in the afternoon when the lunar shadow leaves the U.S.

452 The theoretical maximum number of seconds that a total eclipse could last on Earth.

9:05 The time in the morning of Aug. 21 when the eclipse first crosses into the United States, at Lincoln Beach, Oregon.

2024 The next year when a total solar eclipse will pass through the continental United States.

35,000 The number of people expected to visit Casper to witness the eclipse.

60,000 The number of people who live in Casper. 

12.25 million The number of people who live within the path of totality.

Sources: NASA, National Weather Service,, Astronomy Magazine

Follow managing editor Joshua Wolfson on Twitter @joshwolfson